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Updated: Aug 11, 2026
Feeder-free Derivation of Melanocytes from Human Pluripotent Stem Cells
Published on: March 3, 2016
Normal human melanocytes that express a bFGF transgene still require exogenous bFGF for growth in vitro
1Division of Biomedical Sciences, University of California, Riverside, USA.
Abstract:
The expression of basic fibroblast growth factor (bFGF) has been implicated as an important factor in the development of malignant melanoma. The timing of this expression suggests that bFGF plays a role early in melanoma tumor progression. Benign nevi produce bFGF, and cells cultured from these lesions show a loss of dependence on exogenous bFGF for growth. We have examined the effects of constitutive bFGF expression on the in vitro growth requirements of normal human melanocytes. bFGF was overexpressed in normal human epidermal melanocytes through genomic insertion of a human bFGF cDNA in a retroviral vector. These melanocytes produced the 18 kDa bFGF isoform as well as the higher molecular weight isoforms. The bFGF was not released into the culture medium, but it was present in the cell nucleus. The bFGF produced by these cells was mitogenic for 3T3 fibroblasts and therefore possessed functional activity; however, melanocytes producing bFGF had the same appearance and growth patterns as those infected with control virus or uninfected melanocytes. Expression of bFGF did not confer independence from the exogenous mitogen, nor would these cells form colonies in a soft-agar medium. These results indicate that expression of bFGF alone is not enough to cause aberrant growth of normal human melanocytes.
Insights
Basic fibroblast growth factor (bFGF) expression alone does not cause abnormal growth in normal human melanocytes. Constitutive bFGF production did not lead to growth factor independence or soft-agar colony formation in vitro.
Area of Science:
- Oncology
- Cell Biology
- Dermatology
Background:
- Basic fibroblast growth factor (bFGF) is implicated in malignant melanoma development.
- bFGF expression timing suggests a role in early melanoma progression.
- Benign nevi produce bFGF, and their cells lose dependence on external bFGF.
Purpose of the Study:
- To investigate the effects of constitutive bFGF expression on normal human melanocyte growth requirements.
- To determine if bFGF overexpression alone can induce aberrant growth in melanocytes.
Main Methods:
- Normal human epidermal melanocytes were genetically modified to overexpress bFGF using a retroviral vector.
- Produced bFGF isoforms were identified (18 kDa and higher molecular weight).
- Localization of bFGF (intracellular, nuclear) and its mitogenic activity on fibroblasts were assessed.
Main Results:
- Melanocytes overexpressing bFGF produced functional, mitogenic bFGF, primarily localized in the nucleus.
- Despite bFGF production, these cells maintained normal morphology and growth patterns.
- Overexpression did not confer independence from exogenous growth factors or enable soft-agar colony formation.
Conclusions:
- Constitutive expression of basic fibroblast growth factor (bFGF) alone is insufficient to induce aberrant growth in normal human melanocytes.
- bFGF's role in melanoma progression likely requires additional factors beyond its mere expression.
- Further research is needed to understand the complex mechanisms driving melanoma development.
